Also consider that not everyone can spend $1000, and a large community is also what drives a product. Because it generates more options. Adobe became so popular because early on their software was copied all over the internet (There are studies on this). Basically what Photoshop did at the time was to create a copy of AMIGAs Deluxe Paint. Today Adobe has a very high priced business model, yielding alternatives like Blender in the process, at least in part because of this. To counter this law, Adobe aggressively works to just buy out alternatives. In my opinion pay to play (in order to create) models are dated, and the time of Adobe, Apple, with their protected, restricted concepts is really coming to an end. Unity can only exist so far since they offer a streamlined version, have a solid and active user base.
Unreal is likely to gain more market shares in future years, the product is becoming wider adopted, and more user friendly - sophisticated. Unity and Unreal will likely continue to coexist and benefit from each other in future years. If Unreal would require a $1000 it would result in a disadvantage, driving users to alternatives, meaning less market assets, because it would become more niche etc etc.
Yup, it’s good that you can use Unreal for free if you are making less than $3000 per quarter. Same with Unity if you make less than $100000 per year - use it for free.